Airbnb unveiled new versions of its mobile apps and a series of additional features Tuesday morning during an event for hundreds of hosts in the sleek and expansive lobby of the company's new headquarters.

But the clear secondary purpose of Airbnb Open was to answer ongoing criticisms of the 5-year-old San Francisco company, which allows people to rent their apartments or rooms to travelers.

Various cities, including New York and San Francisco, have struggled to find the appropriate way to regulate the company's "sharing" business model, which enables homeowners, landlords and tenants to act as entrepreneurs in their own right.

Temporarily renting out spaces can sometimes violate traditional housing laws. There's growing concern that some landlords are taking apartments off the market for permanent city residents in favor of renting them for higher prices to Airbnb travelers. And guests have occasionally been known to vandalize apartments and aggravate neighbors.

But in presentations Tuesday - a few that dipped into schmaltz - the founders and executives argued that Airbnb serves a higher purpose than merely making extra money or finding cheap accommodations.

Gaming company Zynga, a block deeper into SoMa from Airbnb, says with a straight face that it is "connecting the world through games." In much the same way, Airbnb contends its hosts and guests are forming bonds across international borders, enabling people to take a trip without leaving their kitchen.

Various anecdotes of this sort were shared, including a tale of a host and guest who turned out to have both been Berlin Wall guards, but on opposite sides of the border.

The word "community" came up about a dozen times, but I'm not sure I heard the word "customer" (or revenue or profit).

"This is a new economy, the sharing economy," said Brian Chesky, chief executive officer and co-founder of Airbnb, noting the company now has 350,000 hosts around the world. "It's actually starting to feel like a revolution. It's a people-powered economy."

Or ... some people need places to stay and some people have extra space, and putting them in touch is a perfectly helpful service that isn't going to elevate the world to a higher plane. Who knows?

Chesky said the regulatory challenges have arisen because they've helped create a category that the law hasn't addressed in the past - not an individual and not a business, but a "micro-entrepreneur."

"There are no laws written for micro-entrepreneurs," Chesky said. "So right now, we're having conversations with local governments and there's good news: The more people hear about us, the more they love us. What they hear is, 'We're strengthening their cities.' "

Indeed, some progress is being made. But other legal battles are still raging. Early last month, Airbnb changed its tune on the issue of taxes, saying its hosts should pay the same ones long levied on hotels, though with some exemptions for people who earn under a certain threshold.

Meanwhile, San Francisco Supervisor David Chiu is leading discussions to legitimize the sharing-business model, while addressing some of the concerns about tenant protections and total housing stock. City sources say his legislation will probably be introduced toward the end of the year.

Things have proved trickier in New York City, where the law restricts rentals for less than 30 days if the owner isn't present. A judge ruled that one East Village resident was effectively operating an illegal hotel, though that decision was recently overturned.

Meanwhile, the New York attorney general is conducting a broad probe into the business, exploring how much is owed on the tens of millions in fees that top hosts have collected and the impact of effectively turning for-rent apartments into de facto hotels.

"Airbnb isn't standing up for average New Yorkers who rent out their apartments from time to time," an attorney general spokesman told the New York Times. "Airbnb is standing up for highly profitable, illegal businesses that make up a huge chunk of its corporate revenue."